Franco Frattini, the commissioner for justice, freedom and security, is to seek the measure in a bid to harmonise penalties for cross-border organised crime in the 25 member states.

Sources close to Frattini say he feels that the Union needs a more ambitious approach to tackling criminal networks than the current policy, which was adopted by EU governments in 1998.

He will argue that the jail sentence imposed for heading a criminal organisation should be not less than a decade. For recruiting criminals or providing material or financial aid to the criminal underworld, a minimum sentence of five years in jail will be urged.

But the proposal provides for a lenient approach to be taken to criminals who turn state’s witness and give evidence against their former associates.

Commission officials contend that such leniency is necessary if crime networks are to be dismantled.

The proposal is to be adopted by the Commission at its 19 January meeting.

Joanna Apap from the Centre for European Policy Studies predicted that such measures could eventually lead to an EU criminal code, which would be overseen by a chamber in the European Court of Justice.

But she said that implementing the measures could prove problematic because of the different approaches in EU states, particularly in relation to human-trafficking. In Spain and Malta, for instance, both the transporting and the illegal entry of migrants are punishable, whereas in Belgium only the former is.

“We need to establish who we should really criminalise – the trafficker or the immigrant,” she added. “There is a risk of putting them both in same basket.”

Stephen Jakobi from the campaign group Fair Trials Abroad argued that the question of minimum sentences should be treated with caution.

He said that he was aware of a case where an Englishwoman on social security had been wrongly convicted of being a mafia boss by an Italian court.

“Minimum sentences are foreign to British law,” he added. “The question of sentences is something that is normally one of judicial discretion, though if a sentence is considered too low, the attorney-general can appeal. So why should there be minimum sentences?”

But Daniel Keohane of the Centre for European Reform believes there should be no difficulty in proposing harmonised minimum sentences. “But the fight against organised crime is not just about laws, it is also about how the police cooperate on key issues such as infiltrating gangs. In that respect, it is quite similar to counter-terrorism,” he said.